Think I'm going to go with the Primitive 3/16 stuff myself (sump/diff guard). The cars going to be mainly on tarmac to rough tarmac and occasionally dirt. I've encountered plenty of rocks though more then capable of tearing nice holes in oil pans, especially if hit with any kind of force simply just strewn across even the nicely paved tarmac back roads here. I've been fortunate enough to avoid this stuff myself for the most part but long oil trail stains on many of the roads are left behind by lots of others who haven't been as fortunate. And if your out in the middle of nowhere with no help around an empty oil pan is not a good thing.
Other stuff I would be interested in if someone started making it would be a prop shaft guard of some sort, and maybe some less expensive floor/fender well protection as the carbon kevlar stuff is sort of out of the budget haha. I may just try and see why I can come up with in the line of some floorboard protection in a less exotic material.